Textual errors in Chapter 7: Numbers #29

In https://github.com/divilian/cool-brisk-walk/blob/master/numbers.tex there is an error:

• Line 862: says "$\texttt{FF}{16}$), which is $256{10}$." but shouldn't it be 255?

In https://github.com/divilian/cool-brisk-walk/blob/master/numbersEx.tex there are 2 errors:

• Line 89 states: "left over. So they're not congruent mod 7." but shouldn't it say they are congruent?
• Line 195 states: "Simple: $1111001011001110_{2}$. Read it right off the chart." but shouldn't it be 1111 1010 1100 1110? What is written looks more like F2CE.

I'm happy to try making a PR with these fixes if I'm not off-base.